No building, accessory building or structure shall be erected within the 15-foot strip of land measured landward from the Rock River from any existing river wall or bulkhead line or encroachment line where a bulkhead line has not been established. This provision does not apply to piers, docks, walks, bridges, culverts, dikes, riverbank erosion control or underground utilities.

(Code 1976, § 18.32.100)